package com.app.script;

import com.app.Context;
import com.app.token.GenericTokenParser;
import com.app.token.TokenHandler;

import java.util.Map;

public class ForEachFragment implements SqlFragment {

    public static final String ITEM_PREFIX = "__frch_";

    private ExpressionEvaluator evaluator;
    private String collectionExpression;
    private SqlFragment contents;
    private String open;
    private String close;
    private String separator;
    private String item;
    private String index;

    public ForEachFragment(SqlFragment contents, String collectionExpression,
                           String index, String item, String open, String close,
                           String separator) {

        this.contents = contents;

        this.evaluator = new ExpressionEvaluator();
        this.collectionExpression = collectionExpression;
        this.index = index;
        this.item = item;
        this.open = open;
        this.close = close;
        this.separator = separator;

    }

    public boolean apply(Context context) {

        Map<String, Object> bindings = context.getBinding();
        final Iterable<?> iterable = evaluator.evaluateIterable(
                collectionExpression, bindings);
        boolean first = true;
        applyOpen(context);
        int i = 0;
        for (Object o : iterable) {
            Context oldContext = context;
            if (first) {
                context = new PrefixedContext(context, "");
            } else {
                if (separator != null) {
                    context = new PrefixedContext(context, separator);
                } else {
                    context = new PrefixedContext(context, "");
                }
            }
            int uniqueNumber = context.getUniqueNumber();
            if (o instanceof Map.Entry) { // Issue #709
                @SuppressWarnings("unchecked")
                Map.Entry<Object, Object> mapEntry = (Map.Entry<Object, Object>) o;
                applyIndex(context, mapEntry.getKey(), uniqueNumber);
                applyItem(context, mapEntry.getValue(), uniqueNumber);
            } else {
                applyIndex(context, i, uniqueNumber);
                applyItem(context, o, uniqueNumber);
            }
            contents.apply(new FilteredContext(context, index, item,
                    uniqueNumber));
            if (first)
                first = !((PrefixedContext) context).isPrefixApplied();
            context = oldContext;
            i++;
        }
        applyClose(context);
        return true;
    }

    private void applyIndex(Context context, Object o, int i) {
        if (index != null) {
            context.bind(index, o);
            context.bind(itemizeItem(index, i), o);
        }
    }

    private void applyItem(Context context, Object o, int i) {
        if (item != null) {
            context.bind(item, o);
            context.bind(itemizeItem(item, i), o);
        }
    }

    private void applyOpen(Context context) {
        if (open != null) {
            context.appendSql(open);
        }
    }

    private void applyClose(Context context) {
        if (close != null) {
            context.appendSql(close);
        }
    }

    private static String itemizeItem(String item, int i) {
        return new StringBuilder(ITEM_PREFIX).append(item).append("_")
                .append(i).toString();
    }

    private static class FilteredContext extends Context {
        private Context delegate;
        private int index;
        private String itemIndex;
        private String item;

        public FilteredContext(Context delegate, String itemIndex, String item,
                               int i) {
            super(null, null);
            this.delegate = delegate;
            this.index = i;
            this.itemIndex = itemIndex;
            this.item = item;
        }

        @Override
        public Map<String, Object> getBinding() {
            return delegate.getBinding();
        }

        @Override
        public void bind(String name, Object value) {
            delegate.bind(name, value);
        }

        @Override
        public String getSql() {
            return delegate.getSql();
        }

        @Override
        public void appendSql(String sql) {
            GenericTokenParser parser = new GenericTokenParser("#{", "}",
                    new TokenHandler() {
                        public String handleToken(String content) {
                            String newContent = content.replaceFirst("^\\s*"
                                            + item + "(?![^.,:\\s])",
                                    itemizeItem(item, index));
                            if (itemIndex != null && newContent.equals(content)) {
                                newContent = content.replaceFirst("^\\s*"
                                                + itemIndex + "(?![^.,:\\s])",
                                        itemizeItem(itemIndex, index));
                            }
                            return new StringBuilder("#{").append(newContent)
                                    .append("}").toString();
                        }
                    });

            delegate.appendSql(parser.parse(sql));
        }

        @Override
        public int getUniqueNumber() {
            return delegate.getUniqueNumber();
        }

    }

    private class PrefixedContext extends Context {
        private Context delegate;
        private String prefix;
        private boolean prefixApplied;

        public PrefixedContext(Context delegate, String prefix) {
            super(null, null);
            this.delegate = delegate;
            this.prefix = prefix;
            this.prefixApplied = false;
        }

        public boolean isPrefixApplied() {
            return prefixApplied;
        }

        @Override
        public Map<String, Object> getBinding() {
            return delegate.getBinding();
        }

        @Override
        public void bind(String name, Object value) {
            delegate.bind(name, value);
        }

        @Override
        public void appendSql(String sql) {
            if (!prefixApplied && sql != null && sql.trim().length() > 0) {
                delegate.appendSql(prefix);
                prefixApplied = true;
            }
            delegate.appendSql(sql);
        }

        @Override
        public String getSql() {
            return delegate.getSql();
        }

        @Override
        public int getUniqueNumber() {
            return delegate.getUniqueNumber();
        }
    }

}
